The minister criticised 'No' campaigners for bringing adoption and surrogacy into the debate on same-sex marriage.

Mr Varadkar said "the mask really slips" when the 'No' campaign raises such issues in referendum debates.

"The number of people who avail of surrogacy every year is absolutely tiny - and almost all of them are straight couples.

"It's already the case that under our laws on surrogacy and adoption, we don't discriminate against single people, unmarried couples or gay people," he told the Irish Independent.

The Health Minister said the 'No' campaign were not only opposed to marriage equality, but "they want to bring in whole new forms of discrimination against single people, unmarried couples, and gay people that don't already exist".

"There is a long history in Ireland of people who have a weak argument trying to bring in extraneous issues into referendum debates.

"I don't know how many times people tried to turn referendums on Europe into referendums on Nato, conscription and abortion.

"We had all the same issues in the divorce referendum 20 years ago that we are now getting from the 'No' campaign. According to opponents at the time, divorce was going to redefine marriage and destroy families. It clearly didn't. I am absolutely confident the Irish people will see through these arguments again."